Where do the counterions go? Tip-induced dissociation of self-assembled triazatriangulenium-based molecules on Au(111).

Chemical coupling of functional molecules on top of the so-called platform molecules allows the formation of functional self-assembled monolayers (SAMs). An often-used example of such a platform is triazatriangulenium (TATA), which features an extended aromatic core providing good electronic contact to the underlying metal surface. Here, we present a study of the SAM formation of a TATA platform on Au(111) employing scanning tunneling microscopy (STM) under ambient atmospheric conditions. In solution, the TATA platform is stabilized by BF4 counterions, while after deposition on a gold substrate, the localization of the BF4 counterions remains unknown. We used 1,2,4-trichlorobenzene as a solvent of TATA-BF4 to induce SAM formation on a heated (∼50 °C) Au substrate. We show by STM how to detect and distinguish TATA-BF4 from TATA platforms, which lost their BF4 counterions. Finally, we observe a change of the counterion position on the SAM during the STM scanning, which we explain by an electric-field-induced decrease of the electrostatic interaction in TATA-BF4 on the surface. We applied DFT calculations to reveal the influence of the gold lattice and the electric field of the STM tip on the stability of TATA-BF4 physisorbed on the surface.

Facile, non-destructive characterization of 2d photonic crystals using UV-vis-spectroscopy.

We present a simple and non-destructive method for characterizing and quantifying the quality of two-dimensional (2D) close-packed arrays of submicron dielectric spheres. Utilizing radiative losses of photonic modes created by the 2D crystals into dielectric substrates we are able to monitor the quality of the particle monolayer during assembly and the size evolution of the individual particles during dry etching. Using an advanced interfacial assembly technique we prepare particle monolayers on glass and characterize the spectral behaviour of the radiative loss regarding different lattice constants, dielectric substrates and layer qualities. The effect of diameter reduction during dry etching is analysed and a simple model is proposed, which enables non-destructive, on spot characterization of the particle layer with sub-20 nm resolution using UV-vis spectroscopy.

Shot Noise of 1,4-Benzenedithiol Single-Molecule Junctions.

We report measurements of the shot noise on single-molecule Au-1,4-benzenedithiol-Au junctions, fabricated with the mechanically controllable break junction (MCBJ) technique at 4.2 K in a wide range of conductance values from 10(-2) to 0.24 conductance quanta. We introduce a simple measurement scheme using a current amplifier and a spectrum analyzer and that does not imply special requirements regarding the electrical leads. The experimental findings provide evidence that the current is carried by a single conduction channel throughout the whole conductance range. This observation suggests that the number of channels is limited by the Au-thiol bonds and that contributions due to direct tunneling from the Au to the π-system of the aromatic ring are negligible also for high conductance. The results are supported by quantum transport calculations using density functional theory.

Negative language use of the physiotherapist in low back pain education impacts anxiety and illness beliefs: A randomised controlled trial in healthy respondents.

OBJECTIVE: This study aimed to determine the effect of physiotherapists' negative language use on nocebo effects of state anxiety and illness beliefs. METHODS: A web-based randomised controlled trial included adults without recent musculoskeletal pain. The intervention was a short educational video about low back pain using negative language (nocebo condition: n = 87) versus a video using neutral or positive language (control condition: n = 82). State anxiety was assessed using the State-Trait Anxiety Inventory. Illness beliefs were assessed using the Illness Perception Questionnaire. RESULTS: Nocebo and control groups differed in outcome measures (MANOVA Pillai's trace = 0.22, F = 4.98; df = (9,159), p < 0.001). Post-hoc analyses showed a medium to large effect for the nocebo condition on anxiety (d = 0.71, 95% CI 0.4 -1.0). The nocebo group also had higher scores in three illness beliefs: beliefs on timeline (d = 0.45, 95% CI 0.14 - 0.75), treatment control (d = 0.43, 95% CI 0.12 - 0.74) and concern (d = 0.47, 95% CI 0.16 - 0.78). CONCLUSION: Physiotherapists' use of negative language contributes directly to a higher state anxiety and illness beliefs that can trigger the nocebo effects in the recipient PRACTICE IMPLICATIONS: Negative language use should be avoided.

Subharmonic resonant optical excitation of confined acoustic modes in a free-standing semiconductor membrane at GHz frequencies with a high-repetition-rate femtosecond laser.

We propose subharmonic resonant optical excitation with femtosecond lasers as a new method for the characterization of phononic and nanomechanical systems in the gigahertz to terahertz frequency range. This method is applied for the investigation of confined acoustic modes in a free-standing semiconductor membrane. By tuning the repetition rate of a femtosecond laser through a subharmonic of a mechanical resonance we amplify the mechanical amplitude, directly measure the linewidth with megahertz resolution, infer the lifetime of the coherently excited vibrational states, accurately determine the system's quality factor, and determine the amplitude of the mechanical motion with femtometer resolution.

Unveiling unconventional magnetism at the surface of Sr2RuO4.

Materials with strongly correlated electrons often exhibit interesting physical properties. An example of these materials is the layered oxide perovskite Sr2RuO4, which has been intensively investigated due to its unusual properties. Whilst the debate on the symmetry of the superconducting state in Sr2RuO4 is still ongoing, a deeper understanding of the Sr2RuO4 normal state appears crucial as this is the background in which electron pairing occurs. Here, by using low-energy muon spin spectroscopy we discover the existence of surface magnetism in Sr2RuO4 in its normal state. We detect static weak dipolar fields yet manifesting at an onset temperature higher than 50 K. We ascribe this unconventional magnetism to orbital loop currents forming at the reconstructed Sr2RuO4 surface. Our observations set a reference for the discovery of the same magnetic phase in other materials and unveil an electronic ordering mechanism that can influence electron pairing with broken time reversal symmetry.

Influence of chopped laser light onto the electronic transport through atomic-sized contacts.

This paper reports on the influence of laser irradiation onto the electrical conductance of gold nanocontacts established with the mechanically controllable breakjunction technique. We concentrate here on the study of reversible conductance changes which can be as high as 200%. We investigate the dependence on the initial conductance of the contacts, the wavelength, the intensity and position of the laser spot with respect to the sample. Under most conditions an enhancement of the conductance is observed. We discuss several physical mechanisms which might contribute to the observed effect including thermal expansion, rectification and photon-assisted transport. We conclude that thermal expansion is not the dominating one.

Creation of equal-spin triplet superconductivity at the Al/EuS interface.

In conventional superconductors, electrons of opposite spins are bound into Cooper pairs. However, when the superconductor is in contact with a non-uniformly ordered ferromagnet, an exotic type of superconductivity can appear at the interface, with electrons bound into three possible spin-triplet states. Triplet pairs with equal spin play a vital role in low-dissipation spintronics. Despite the observation of supercurrents through ferromagnets, spectroscopic evidence for the existence of equal-spin triplet pairs is still missing. Here we show a theoretical model that reveals a characteristic gap structure in the quasiparticle density of states which provides a unique signature for the presence of equal-spin triplet pairs. By scanning tunnelling spectroscopy we measure the local density of states to reveal the spin configuration of triplet pairs. We demonstrate that the Al/EuS interface causes strong and tunable spin-mixing by virtue of its spin-dependent transmission.

Comparison of cryogenic low-pass filters.

Low-temperature electronic transport measurements with high energy resolution require both effective low-pass filtering of high-frequency input noise and an optimized thermalization of the electronic system of the experiment. In recent years, elaborate filter designs have been developed for cryogenic low-level measurements, driven by the growing interest in fundamental quantum-physical phenomena at energy scales corresponding to temperatures in the few millikelvin regime. However, a single filter concept is often insufficient to thermalize the electronic system to the cryogenic bath and eliminate spurious high frequency noise. Moreover, the available concepts often provide inadequate filtering to operate at temperatures below 10 mK, which are routinely available now in dilution cryogenic systems. Herein we provide a comprehensive analysis of commonly used filter types, introduce a novel compact filter type based on ferrite compounds optimized for the frequency range above 20 GHz, and develop an improved filtering scheme providing adaptable broad-band low-pass characteristic for cryogenic low-level and quantum measurement applications at temperatures down to few millikelvin.

Identification of the current path for a conductive molecular wire on a tripodal platform.

We present the chemical synthesis as well as charge transport measurements and calculations for a new tripodal platform based on a rigid 9,9'-spirobifluorene equipped with a phenylene-ethynylene wire. The transport experiments are performed with the help of the low-temperature mechanically controlled break junction technique with gold electrodes. By combining experimental and theoretical investigations of elastic and inelastic charge transport, we show that the current proceeds through the designated molecular wire and identify a binding geometry that is compatible with the experimental observations. The conductive molecular wire on the platform features a well-defined and relatively high conductance of the order of 10(-3)G0 despite the length of the current path of more than 1.7 nm, demonstrating that this platform is suitable to incorporate functional units like molecular switches or sensors.

Signature of magnetic-dependent gapless odd frequency states at superconductor/ferromagnet interfaces.

The theory of superconductivity developed by Bardeen, Cooper and Schrieffer (BCS) explains the stabilization of electron pairs into a spin-singlet, even frequency, state by the formation of an energy gap within which the density of states is zero. At a superconductor interface with an inhomogeneous ferromagnet, a gapless odd frequency superconducting state is predicted, in which the Cooper pairs are in a spin-triplet state. Although indirect evidence for such a state has been obtained, the gap structure and pairing symmetry have not so far been determined. Here we report scanning tunnelling spectroscopy of Nb superconducting films proximity coupled to epitaxial Ho. These measurements reveal pronounced changes to the Nb subgap superconducting density of states on driving the Ho through a metamagnetic transition from a helical antiferromagnetic to a homogeneous ferromagnetic state for which a BCS-like gap is recovered. The results prove odd frequency spin-triplet superconductivity at superconductor/inhomogeneous magnet interfaces.

Subjective ordering, short-term memory, and the frontal lobes.

Four tasks relying on short-term retention, i.e. digit span, missing scan, randomization span, and pointing span were presented to patients with frontal-lobe lesions and normal controls. Digit span was considered a measure of passive short-term memory, the other three tasks additionally reflect comparing processes, and two of these, the randomization and pointing spans, also measure active ordering by the subject. The results confirmed Petrides and Milner's (Neuropsychologia 20, 249-262, 1982) hypothesis that frontal-lobe patients are typically deficient in subject-ordered tasks. It is also suggested that they are deficient in a spontaneous generation, rather than comparison component of subjective ordering.

Increased incidence of anti-dsDNA autoantibody concentration in sera of workers occupationally exposed to diisocyanates.

Sera of 87 industrial workers with a history of occupational exposition to various diisocyanates, toluene diisocyanate, hexamethylene diisocyanate and methylene-diphenyl diisocyanate were analyzed for antibodies to isocyanate-conjugated human serum albumin and for anti-dsDNA autoantibodies. Ten workers (approx. 11%) were shown to have elevated anti-dsDNA autoantibody concentrations and 13 revealed antibodies to isocyanate-modified human serum albumin. The overlap of both tests being positive was calculated at about 40%. It would seem, therefore, that routine estimation of anti-dsDNA autoantibodies could provide additional useful information for the clinical diagnosis of occupational health impairment due to isocyanate exposure.

Action of substance P and an analogue on blood pressure and avoidance learning in rats with spontaneous hypertension (SHR).

Substance P (SP) and an analogue (Lys-Phe-Ile-Gly-Leu-MetNH2 = EH) were tested in acute experiments on the blood pressure in the intact rat anaesthetized with urethane. A biphasic response, consisting of an initial depressor, followed by a pressor component, was seen. In low concentrations, SP decreases blood pressure, in medium concentrations SP produces a pronounced biphasic response, in high concentrations SP produces only hypertensive reactions. In chronic experiments, SP-peptides act also in different directions. After EH, disorders in avoidance learning were completely eliminated from 10 weeks old spontaneously hypertensive rats (SHR) or conditionally from SHR age 14 or 26 weeks. Elevated blood pressure in SHR aged 26 weeks was reduced by EH. Blood pressure in SHR aged 14 weeks was almost unaffected by EH and blood pressure went up in ten weeks old SHR. SP had a weaker action in comparison with EH. These results are in agreement with the hypothesis proposed by Oehme and co-workers [11-13] that SP can act as a regulatory peptide (="regulide").

[The health status and health care use of elderly living in sheltered residences. A comparison with independently living elderly]. / Gezondheidstoestand en zorggebruik van bewoners van service-ouderenwoningen. Een vergelijking met zelfstandig wonenden.

A sheltered residence for older persons is a living arrangement in between independent living and a residential institution. There is little knowledge about the health of elderly living in these residences. We studied the physical, functional and psychosocial health of 401 persons living in a sheltered residence for elderly in Zwolle through a standardised interview. We compared the health of these elderly to the health of independently living elderly in the same region studied in the Longitudinal Aging Study Amsterdam and adjusted for sex, age and married state. We found an impaired functional health and more chronic illnesses among elderly living in a sheltered residence. In addition, more medication was used (OR = 2.4). The studied elderly felt more often depressed (OR = 1.9) or lonely (OR = 1.7). Their mental state was more frequently impaired (OR = 1.7), they visited health professionals more often and received more help for personal care (OR = 2.0) and housekeeping (OR = 1.6). We conclude that people living in sheltered residences form a distinct group of elderly, characterised by impaired physical, functional and psychosocial health. Planners of future care must be aware of this vulnerable group.

A current-driven single-atom memory.

The possibility of fabricating electronic devices with functional building blocks of atomic size is a major driving force of nanotechnology. The key elements in electronic circuits are switches, usually realized by transistors, which can be configured to perform memory operations. Electronic switches have been miniaturized all the way down to the atomic scale. However, at such scales, three-terminal devices are technically challenging to implement. Here we show that a metallic atomic-scale contact can be operated as a reliable and fatigue-resistant two-terminal switch. We apply a careful electromigration protocol to toggle the conductance of an aluminium atomic contact between two well-defined values in the range of a few conductance quanta. Using the nonlinearities of the current-voltage characteristics caused by superconductivity in combination with molecular dynamics and quantum transport calculations, we provide evidence that the switching process is caused by the reversible rearrangement of single atoms. Owing to its hysteretic behaviour with two distinct states, this two-terminal switch can be used as a non-volatile information storage element.